This invention relates in general to apparatus and processes for supporting cylinders.
Various techniques have been devised to clean and coat cylindrical substrates. Substrate support elements are necessarily postioned within the interior of the hollow cylinder to ensure noninterference with the application of the coating to the exterior surface of the cylinder. When hollow metal cylinders are coated with solutions of film forming polymers, variations in the texture and thickness of the coating occurs due to nonuniform heat transfer between the metal substrate and support elements within the hollow cylinder during heat drying and cooling of the coated cylinders. It is believed that the devices utilized to support the substrates tend to cause coating non-uniformities by drawing heat away from isolated contact spots on the substrate (heat sinking). Nonuniformity in the texture and thickness of the applied coatings is particularly undesirable for coatings in electrostatographic imaging members because even slight variations in the coating can adversely affect electrical properties of the final product. Moreover, some supports are attacked by solvents used during application of coatings to the substrates resulting in deterioration of the support. Also, repeated sliding contact between substrates and the support devices during reuse of the support devices can cause erosion of the support which in turn generates particulates that contaminate the final coating on the substrate. Further, depending upon the material utilized in the support, the support can be a source of undesirable vaporous contamination.
In addition, accurate allignment of a cylindrical substrate relative to the source of coating application devices can be difficult to achieve with many support devices. Where hollow cylinders are supported by cantilevered arms, particularly arms arranged concentrically around a central coating application source, careful control of the distance between the source of the coating material and the surface of the hollow cylinder to be coated is extremely important. Where there is play between the cantilevered arm and the interior of the supported hollow cylinders, the play can cause variations in distances between different locations on a given cylinder and the coating source.
Other disadvantages of prior art systems are the long cycle times to load and unload cylinders and the difficulty in automating these prior art systems.
One technique for spacing hollow sleeves from a cantilevered arm having cylindrical cross-section is to use endcaps on each end of the cylinder. The endcaps encircle the exterior of the end of each cylinder and have a flange which extends radially toward the mandrel. Thus, a cross-sectional view of a radial section of the endcaps would take on the appearance of a "T" or a "L" depending on whether the endcap is to be used on a single cylinder or for multiple cylinders where the ends of two cylinders are adjacent to each other. The end view of this type of endcap has the appearance of a washer. One intended purpose for using an endcap is to achieve uniform spacing between the exterior surface of the cylinder and the axis of the cantilevered supporting arm. However, rubbing of the endcap on the supporting cantilevered arm causes wear and eventually play. Also, the rubbing causes undesirable debris to form. Also endcaps have considerable mass and can cause nonuniform heating of the ends of the cylinders which, in turn, adversely affect coating uniformity.